Pressure gage



Aug. 25, 1964 P. GRANDSTAFF 3,145,570

PRESSURE GAGE Filed May 16, 1961 s Sheets-Sheet 1 INVENTOR. PE A AMDQ Av l Lil":

Aug. 25, 1964 P. GRANDSTAFF PRESSURE-GAGE 5 Sheets-Sheet 3 Filed May 16,1961 INVENTOR. P RRY GR T FF United States Patent 01 Fice 3,145,570Patented Aug. 25, 1964 3,145,570 PRESSURE GAGE Perry Grandstafl,Oklahoma City, Okla, assignor to Drilling Equipment Manufacturing Co.,Oklahoma City, 01:121., a corporation of Oklahoma Filed May 16, 1961,Ser. No. 110,372 4 Claims. (Cl. 73-419) This invention relates topressure gages, and more particularly to improvements in theconstruction of fluid pressure gages and deflecting mechanisms therefor.

The principal objects of the present invention are: to provide apressure gage of extremely simple construction which is adjustable indeflection rate, as well as load range; to provide such a gage whichincludes a simple adjusting member for calibrating the gage spring toachieve the exact deflection rate desired; to provide such a gageconstruction wherein high pressures may be measured while maintaininglow pressures and forces on sensitive parts of the gage; to provide agage assembly having a reciprocally mounted piston hydraulically movablewithout the use of high friction sliding seals heretofore necessary tocontrol leakage past the piston; to provide such a gage constructionhaving a sensing assembly isolated from the gage assembly, butcommunicating therewith by means of a trapped pressure-transmittingfluid which is in turn isolated from the fluid being measured; toprovide a gage construction which substantially eliminates thepossibility of corrosive fluids entering the gage assembly; to providesuch a construction wherein the isolating pressuredransmitting fluidprovides damping of the gage by restricting the free flow of said fluid;to provide such a device which is adaptable for measuring mud pressurein the drilling of wells, as well as finding many other industrialapplications; and to provide such a pressure gage which is inexpensiveto produce and yet accurate, repeatable and reliable in use.

Other objects and advantages of this invention will become apparent fromthe following description taken in connection with the accompanyingdrawings wherein are set forth by way of illustration and examplecertain embodiments of this invention.

FIG. 1 is a view in side elevation of a typical gage installationwherein the sensing assembly is remote from the gage assembly.

FIG. 2 is a sectional View on an enlarged scale through the sensingassembly and gage assembly, showing the position of the parts thereinunder zero deflection.

FIG. 3 is a sectional view on an enlarged scale through the-gageassembly, taken on the line 33, FIG. 4.

FIG. 4 is a sectional view on an enlarged scale through the sensingassembly and gage assembly showing the parts therein under deflection.

FIG. 5 is a fragmentary sectional view on an enlarged scale showing arack and pinion used in the gage assembly to translate reciprocatorymotion into rotary motion.

FIG. 6 is a view in side elevation of a mud pressure gage installed on atypical stand pipe on a drilling mud line.

FIG. 7 is a sectional view on an enlarged scale of the mud pressuregage, taken on the line 77, FIG. 8.

FIG. 8 is a view in side elevation on an enlarged scale of the mudpressure gage with a portion broken away.

Referring to the drawings in more detail:

The reference numeral 1 indicates a pipe line containing a fluid underhigh pressure. A T fitting 2 is secured in the line 1 and has threadedlyconnected therewith a sensing assembly 3 of a fluid pressure gagegenerally indicated at 4. The fluid pressure gage 4 includes a gageassembly 5 operatively connected to the sensing assembly,

3 with an hydraulic hose 6. The gage assembly 5 is illustrated assecured to the pipe line 1 with suitable brackets 7; however, otherlocations and mounting devices for the gage assembly 5 may be providedwithout departing from the scope of this invention.

The sensing assembly 3 includes a pressure connector 8 having externalthreads 9 and internal threads 10. In the illustration of FIG. 1, theexternal threads 9 are engaged with the T fitting 2.; however, in someinstances, it may be desirable to connect the sensing assembly 3 to thepressure line 1 with an hydraulic hose (not shown) in which case theinternal threads 10 may be utilized.

The pressure connector 8 has a side wall 10' presenting an insidecylindrical side surface 11 and an inside end wall 11' presenting an endsurface 12. The surfaces 11 and 12 define a cylindrical cavity 13. A cap14 exhibits internal threads 15 adapted to be engaged with externalthreads 16 on the outside surface of the wall 10. The'cap 14 closes thecavity 13 for a purpose described hereinafter.

A flexible diaphragm, 17, which is preferably of the type composed ofrubber reinforced with nylon fibers and known as a Bellofram Seal, hasthe periphery 18 thereof secured between the inner surface 19 of the cap14- and the end or terminating edge 20 of the wall 10. The flexiblediaphragm 17 extends into the cavity 13 and divides said cavity into tWochambers respectively designated 21 and 22. A cylindrical piston 23 iscontained in the chamber 21 and is shaped to provide a recessedcylindrical central portion 24 formed by an integral skirt 25 extendingtoward the end surface 12. The piston 23 exhibits an outer surface 26which contacts the flexible diaphragm 17. The outside diameter of thepiston 23, including the skirt 25, is of a size which permits thediaphragm 17 to fold betweenthe inside cylindrical surface 11 and thepiston when the piston is moved toward the cap 14, as best illustratedat 27, FIG. 4.

An elongated plunger 23 exhibits a shank 29, of substantially smallerdiameter than the outside diameter of the piston 23, and a head 30. Abore 31 extends through the end wall 11' and past the end surface 12 andis coaxial with the cavity 13. The plunger shank 29 closely fits andslidably extends through the bore 31 and into the cavity 13. The'plungerhead 31) contacts the inner surface 31 of the piston 23.

A suitable seal such as an O-ring 32 surrounds the plunger shank 23 andis retained thereagainst by means of a threaded packing member 33engaging with internal threads 34 formed in the walls of a depression 34extending into the end wall 11'. The packing member 33 exhibits anannular groove 35 whichcontains the O-ring 32 and forces same againstthe plunger shank 29 and against the end wall 11' to provide anefiicient fluid seal therebetween while permitting reciprocal motion ofthe plunger 28. A drain hole 35' extends through the wall 10 into thechamber 21 to drain any fluid from the connector 8 which bleeds past theO-ring 32.

A pressure-transmitting fluid 36 such as hydraulic fluid iscontainedwithin the chamber 22 and isolated from the chamber 21 by means of theflexible diaphragm 17. The hydraulic hose 6 terminates at one endthereof in a threaded nipple 37 engaging a threaded socket 33 in the cap14. A small bore or damping orifice 39 communicates between the socket38 and the chamber 22 to permit the flow of the fluid 36 therethroughand into the hydraulic hose 6 at a restricted rate and under conditionsdescribed hereinafter. It is noted that both the size of the orifice 39and the viscosity of the fluid 36 affect the rate of flow.

The hydraulic hose 6 terminates at the other end thereof in a threadednipple 40 engaging with a threaded socket '3 a3 41 in a block 42. Theblock 42 is secured to a sleeve 43 by means of elongated screws 44extending longitudinally thereinto, FIG. 4. The sleeve 43 forms a frameor anchoring member for supporting a gauge pointer assembly 45 having apointer 46 rotatably supported thereon by means of a shaft 47. The shaft47 carries a pinion 48 fixed thereto and engaged with a rack 49 whichisreciprocally guided in a groove 50 for rotating the pinion 48. A leafspring 56 urges the rack 49 into engagement with the pinion 48. The end51 of the rack 49 is adjustably secured in a bore 52 extending through abar 53 by means of a set screw 54. The bar 53 is threadedly secured to arod 55 extending into the sleeve 43 and longitudinally reciprocable withrespect thereto through apparatus described hereinafter.

A box or container 56 is secured to the sleeve 43 by means of screws 56.The container surrounds the block 42 and sleeve 43 and supports a dialface 57 adjacent the pointer 46. The container 56 also supports aviewing glass 58 to permit sighting the position of the pointer withrespect to the dial face 57.

The block 42 exhibits a cylindrical cavity 59 opening toward the sleeve43 and coaxial with the inside surface 60 of the sleeve 43, the cavity59 and sleeve 43 forming a continuous cylindrical bore 60'. A flexiblediaphragm 61 similar in construction to the diaphragm 17 described abovehas the periphery 62 thereof clamped between the block 42 and the sleeve43. The diaphragm 61 extends into the cavity 59 and divides the bore 60and cavity 59 into two chambers 63 and 64 respectively. The block 42also contains a bore or damping orifice 65 communieating between thesocket 41 and the chamber 64 to further restrict the flow of fluid 36 inthe gage. It is apparent that the fluid 36 is trapped within thechambers 64 and 22 but is permitted to flow back and forth therebetweenthrough the hydraulic hose 6 to transmit signals or intelligence fromthe sensing assembly 3 to the gage assembly 5.

A piston 66 is contained in the chamber 63 and is urged into contactwith the flexible diaphragm 61 by meansof a gage spring 67. The piston66 is smaller in diameter than the bore 66 and cavity 59 whereby theflexible diaphragm 61 may fold between the piston 66 and the surface ofthe bore 66' in the manner indicated with respect to the flexiblediaphragm 17. The gage spring 67 is a helical compression spring havinga plurality of wire coils 68 which surround the rod 55. The rod 55 isthreadedly engaged in the piston 66 and moves therewith. The piston 66exhibits a lip 69 forming a socket 69' for retaining one end of thespring 67 coaxial and'in fixed contact therewith.

A retainer or collar 70 contains an axial bore 71 therethrough forslidably receiving the rod 55 and is retained in the sleeve 43 spacedfrom the piston 66 by means of a set screw 72 extending through thesleeve 43, FIG. 2. The collar 76 exhibits a helical groove 73 on theouter surface thereof which leads axially of the rod 55 and is adaptedto adjustably receive one or more of the wire coils 68 of the gagespring 67 to make them inactive. The set screw 72 locks the spring wirein the groove 73 and also adjustably fixes the collar 70 longitudinallywith respect to the sleeve 43. It is apparent that when the spring 67 isrotated with respect to the collar '70, the eifective developed lengthof the spring or, in other words, the number of active wire coils in thespring extending between the collar 76 and piston 66 is altered.

In operation, fluid pressure is exerted against the plunger 28, whichdue to the relatively small cross sectional area of the shank 29 withrespect to the piston 23, proportionally reduces the pressure per unitarea otherwise exerted by the surface 26 of the piston. The fluidpressure causes the plunger 28 to urge the piston 23 against theflexible diaphragm 17 which in turn urges the fluid 36 out of thechamber 22 through the hydraulic hose 6 and into the chamber 64. Theflow of fluid into the chamber 64 is accompanied by an increase inpressure against the flexible diaphragm 61 which causes an axialdisplacement of the piston 66 toward the collar 70, compressing thespring 67. The displacement of the piston 66 is reflected in an axialmovement of the rod 55 which moves the bar 53 resulting in a rotationaldisplacement of the pointer 46.

The sensing assembly 3 has been described as connected to a pressureline, however it is to be noted that the sensing assembly 3 may alsoprovide an intermediate state of pressure reduction for reducingextremely high pressure to pressures suitable for delicate gagestructures. In the latter case one or more additional assemblies such assensing assembly 3 may be arranged in tandem, or in other words, inseries whereby additional fluid containing chambers will be provided.

The configuration of the apparatus described permits an adjustment orcalibration to achieve the desired variation in pointer deflection rate,as well as an adjustment of load range and zero setting withoutreplacement of gage parts. The deflection rate, sometimes referred to asthe gage factor, is altered as described above by rotating the collar 76with respect to the gage spring 67 to add or remove active wire coilsfrom the gage spring. The load range of the gage may be altered byadjusting the axial position of the collar 76 with respect to the sleeve43 to increase or decrease the compression of the spring 67 at any givenpointer deflection. The pointer zero setting may be adjusted withoutinterference with the spring 67 by loosening the set screw 54 and movingthe rack 49 with respect to the bar 53.

Another form of this invention is illustrated in FIGS. 6, 7 and 8wherein a stand pipe 74 is operatively connected to a mud line 75 forwell drilling operation. The pressure gage 76 is characterized in beingencased in a single unit or frame 77 containing a rotatably mountedpointer assembly 78, plunger 79, plunger seal 79', a piston 80, drainhole 30', flexible diaphragm 81, hydraulic fluid 81', damping orifice82, flexible diaphragm 82', piston 83, rod 83' and gage spring 84similar in function to like parts described above. The collar 85 whichsupports one end of the spring 84, however, contains the springsupporting helical groove 86 on the wall of a bore 87 rather than on theoutside surface. The spring 84 is positioned between the rod 83' and thecollar 85. The collar 85 is retained against axial movement away fromthe diaphragm 82 by means of a shoulder 88 formed on a threaded a11-nular ring 89 which is in turn engaged with a supporting sleeve 90 fixedwith respect to the frame 7'1. Load range of the gage 76 may be adjustedby rotating the ring 89 with respect to the sleeve 90 to axiallyposition the collar 85. Deflection rate may be adjusted by rotating thespring 84 with respect to the collar 85. The retention of the springcoils in the collar 85 is satisfactorily achieved by means of frictionalcontact with the grooves 86. The pointer zero setting may be adjustedwith the lock nuts 91.

It is to be understood that While I have illustrated and describedcertain forms of my invention, it is not to be limited to the specificforms or arrangements or parts herein desecribed and shown exceptinsofar as such limitations are included in the claims.

What I claim and desire to secure by Letters Patent is:

l. A fluid pressure gage comprising, a frame having a dial face securedthereto, a gage pointer mounted on said frame and adapted to visuallyexhibit a reading on said dial face, a rod axially reciprocally movablewith respect to said frame, means operatively connecting said pointerand rod for translating the axial position of said rod with respect tosaid frame into a dial reading, a piston secured to said rod and adaptedto move therewith, means adapted to displace said piston in response toa pressure signal for moving said rod, a collar spaced axially of saidpiston,

means for axially adjustably securing said collar with respect to saidframe Without rotation of said collar, said collar having an axial boretheretbrough for slidably receiving said rod, a helical compressionspring acting on said rod, said spring having a plurality of active Wirecoils surrounding said rod and having one end thereof contacting saidpiston, a helical groove on said collar and leading axially of said rod,said groove adjustably receiving said coils at the other end of saidspring in re sponse to relative rotations between said collar and saidspring to change the number of active wire coils extending between saidcollar and said piston, said means for axially adjustably securing saidcollar permitting variations in the compression of said spring withoutalteration of the number of active Wire coils on said spring, wherebysaid gage is adjustable to provide a variation in pointer deflectionrate as well as load range.

2. A deflection rate and load range adjusting device comprising, a frameand a pressure responsive member movable with respect to said frame, ahelical spring having a plurality of active wire coils and having oneend thereof operatively bearing on said pressure responsive member, aretainer normally stationary with respect to said frame, said springhaving the other end thereof operatively bearing against said retainer,means for adjustably securing said retainer on said frame coaxially ofsaid spring without rotation of said retainer for adjusting thecompression of said spring against said pressure responsive member, saidmeans also adjustably securing said retainer on said frame for rotationWith respect to said spring, said retainer having a helical groovetherein adapted to adjustably receive and inactivate selected coilsadjacent the other end of said spring by relative rotation of saidretainer with respect to said spring, whereby the deflection rate andload range of said spring is selectively altered by selective coaxialand rotational adjustment of said retainer.

3. The device of claim 2 wherein said helical groove extends into theouter surface of said retainer.

4. A deflection rate and load range adjusting device comprising, a frameand a pressure responsive member movable with respect to said frame, ahelical spring having a plurality of active wire coils and having oneend thereof operatively bearing on said pressure responsive member, aretainer, said spring having the other end thereof operatively bearingagainst said retainer, means for adjustably securing said retainer onsaid frame coaxially of said spring without rotation of said retainerfor adjusting the compression of said spring against said pressureresponsive member, said retainer having a coaxial bore therethrough, ahelical groove extending into the surface of said bore, said helicalgroove being adapted to adjustably receive and inactivate selected coilsadjacent the other end of said spring by relative rotation of saidretainer with respect to said spring, whereby the deflection rate andload range of said spring is selectively altered.

References Cited in the file of this patent UNITED STATES PATENTS1,400,550 Hopwood Dec. 20, 1921 1,950,532 Wasson Mar. 13, 1934 2,437,440Rigden Mar. 9, 1948 2,661,626 Mofrett Dec. 8, 1953 2,725,749 Green Dec.6, 1955 2,989,991 Knoble June 27, 1961

1. A FLUID PRESSURE GAGE COMPRISING, A FRAME HAVING A DIAL FACE SECUREDTHERETO, A GAGE POINTER MOUNTED ON SAID FRAME AND ADAPTED TO VISUALLYEXHIBIT A READING ON SAID DIAL FACE, A ROD AXIALLY RECIPROCALLY MOVABLEWITH RESPECT TO SAID FRAME, MEANS OPERATIVELY CONNECTING SAID POINTERAND ROD FOR TRANSLATING THE AXIAL POSITION OF SAID ROD WITH RESPECT TOSAID FRAME INTO A DIAL READING, A PISTON SECURED TO SAID ROD AND ADAPTEDTO MOVE THEREWITH, MEANS ADAPTED TO DISPLACE SAID PISTON IN RESPONSE TOA PRESSURE SIGNAL FOR MOVING SAID ROD, A COLLAR SPACED AXIALLY OF SAIDPISTON, MEANS FOR AXIALLY ADJUSTABLY SECURING SAID COLLAR WITH RESPECTTO SAID FRAME WITHOUT ROTATION OF SAID COLLAR, SAID COLLAR HAVING ANAXIAL BORE THERETHROUGH FOR SLIDABLY RECEIVING SAID ROD, A HELICALCOMPRESSION SPRING ACTING ON SAID ROD, SAID SPRING HAVING A PLURALITY OFACTIVE WIRE COILS SURROUNDING SAID ROD AND HAVING ONE END THEREOFCONTACTING SAID PISTON, A HELICAL GROOVE ON SAID COLLAR AND LEADINGAXIALLY OF SAID ROD, SAID GROOVE ADJUSTABLY RECEIVING SAID COILS AT THEOTHER END OF SAID SPRING IN RESPONSE TO RELATIVE ROTATIONS BETWEEN SAIDCOLLAR AND SAID SPRING TO CHANGE THE NUMBER OF ACTIVE WIRE COILSEXTENDING BETWEEN SAID COLLAR AND SAID PISTON, SAID MEANS FOR AXIALLYADJUSTABLY SECURING SAID COLLAR PERMITTING VARIATIONS IN THE COMPRESSIONOF SAID SPRING WITHOUT ALTERATION OF THE NUMBER OF ACTIVE WIRE COILS ONSAID SPRING, WHEREBY SAID GAGE IS ADJUSTABLE TO PROVIDE A VARIATION INPOINTER DEFLECTION RATE AS WELL AS LOAD RANGE.